Relay 1 and 2 were two spacecraft, designed and built by RCA, to test intercontinental satellite communications technology. Relay was a communications satellite of the active repeater type, in which signals from one ground station were picked up and rebroadcast to another station by the satellite's internal equipment. Relay 1 remained operational for more than 2 years; Relay 2 was used in thousands of tests and experiments and in some 40 public demonstrations through September 1965. Both were launched by a Delta rocket from Cape Canaveral and had a mass of 78 kg.

 

spacecraft	launch date	orbit
Relay 1	Dec 13, 1962	1,319 × 7,440 km × 47.5°
Relay 2	Jan 21, 1964	1,961 × 7,540 km × 46.4°